Include termhooks.h.

Include termhooks.h.
(push_key_description): Handle all modifiers.
Handle large character codes.
(Fkey_description): Move the meta bit, if arg is string.
(Fsingle_key_description): Don't alter integer value.
Make tem long enough.

(Flookup_key): Use meta_modifier as meta-bit if from vector.
(Fdefine_key): Likewise.